Field of the Invention
The present invention relates to a remote diagnostic device for a computer-controlled apparatus.
Description of the Related Art
A numerical controller (hereinafter referred to as “CNC”) mounted in a numerically-controlled machine tool is an example of a computer-controlled apparatus. If the CNC in the machine tool suffers a failure that cannot be overcome by a user, the user asks the manufacturer of the CNC for repair on the telephone or the like. The CNC manufacturer asks the user for information on the state of the CNC and gives the user an instruction for processing if the cause of the failure is detected by the notified state. If the machine tool is enabled to normally operate by the taught processing, a serviceman of the CNC manufacturer need not visit the site of the repair.
On the other hand, Japanese Patent Application Laid-Open No. 02-077907, for example, proposes a system in which a serviceman of a CNC manufacturer operates a CNC connected to a communication line from a remote place, thereby investigating the cause of a failure to eliminate the failure. Aided by this system, the serviceman need not visit the site of the failure to overcome the failure.
However, the above-described system is based on the premise that the CNC is previously incorporated with an electrical circuit and software that are required for the connection to the communication line.
In contrast, Japanese Patent Application Laid-Open No. 06-110537, for example, proposes an arrangement in which an external machine-side communication unit is provided separately from a body CNC, in order to remotely maintain a conventional CNC that is not incorporated with such a combination of an electrical circuit and software so that its failure cannot be overcome from a remote place.
FIG. 5 is a block diagram of a remote diagnostic device for the numerically-controlled machine tool disclosed in Japanese Patent Application Laid-Open No. 06-110537.
A machine tool 1 is installed in a factory and it is connected with a control unit 2 of the CNC. The CNC comprises the control unit 2 and a manual data input device with a display unit (hereinafter referred to as “CRT/MDI”) 3. A machine-side communication unit 4 is connected between the control unit 2 and the CRT/MDI 3. The CRT/MDI 3 comprises an output display unit and an operating unit. The output display unit receives from the control unit 2 various diagnostic data on the machine tool 1 as screen information in the form of video signals and displays them on a CRT screen. The operating unit outputs a key operation input as an MDI signal to the control unit 2. The machine-side communication unit 4 performs switching communication control between the control unit 2 and the CRT/MDI 3 or a computer 9 (described later).
A telephone line modem (M) 5 is connected to the machine-side communication unit 4 so that data can be transferred between them through an RS-232C interface. The modem 5 is connected to a telephone line modem (M) 7 on the maintenance side through a public telephone network 6.
A maintenance-side communication unit 8 is connected to the maintenance-side modem 7 by the RS-232C interface, and the diagnostic computer 9 is connected to the maintenance-side communication unit 8. The computer 9 performs fault diagnosis, preventive maintenance, etc., of the numerically-controlled machine tool 1. To this end, the computer 9 receives the various diagnostic data from the control unit 2 and outputs the key operation input signal from the computer 9 as the MDI signal to the control unit 2, based on the result of the diagnosis.
FIG. 6 is a block diagram showing the internal configuration of the machine-side communication unit 4 of FIG. 5.
The video signals from the control unit 2 (FIG. 5) of the CNC are input to a synchronous circuit 4b through a terminal 4a and delivered to the CRT/MDI 3 through a terminal 4c. The output of the synchronous circuit 4b is output to a terminal 4g through a video RAM 4d, data compression unit 4e, and parallel/serial conversion unit (P/S) 4f. The terminal 4g is connected to the modem 5 (FIG. 5). Thus, the input video signals are recorded on the video RAM 4d after they are synchronized in the synchronous circuit 4b. Then, the video signals are compressed to a data capacity suitable for transmission by the public telephone network 6 in the data compression unit 4e, and moreover, converted into serial signals for the public telephone network 6 in the parallel/serial conversion unit 4f and output to the modem 5.
Further, a serial/parallel conversion unit (S/P) 4j is connected to the terminal 4g, and a selector switch 4i is connected to the serial/parallel conversion unit 4j. The selector switch 4i is connected to terminals 4h and 4k. Thus, the selector switch 4i normally connects the terminal 4h to the terminal 4k, and in this case, the MDI signal from the CRT/MDI 3 is sent to the control unit 2 of the CNC. When the fault diagnosis or the like is performed as described later, on the other hand, the selector switch 4i connects the terminal 4h to the serial/parallel conversion unit 4j. In this case, the MDI signal delivered in the form of a serial signal from the computer 9 through the public telephone network 6 is converted into a parallel signal in the serial/parallel conversion unit 4j and then sent to the control unit 2 (FIG. 5). The above-described machine-side communication unit 4 is constructed separately from the CNC and configured to be connected to the CNC by being inserted into a mounting slot of the CNC.
However, the technique disclosed in Japanese Patent Application Laid-Open No. 06-110537 has never been practically used because of the following problems.
A first problem is that there are a wide variety of interfaces used for the display device depending on the type, so that a circuit for converting the video signals must be changed according to the display device.
A second problem is that so many types of actuators are used for key operation that they should be ascertained in advance.
Accordingly, there has not been provided a simple, low-priced remote diagnostic device capable of being used in common for conventional remote-controllable, interface-free CNCs without regard to the types of the CNCs.